First and most blatant, the amount of hit points it actually restores are vanishingly small. A single hit point per level of the affected creature. At first level, the average strike from a simple weapon deals about 4 to 5 damage! Succeeding on a DC 25 Heal check increases the healing by the doctor's Wisdom modifier, but the actual healing remains very small an does not scale at well at all with higher levels as hit points and damage scale at a rising pace and Treat Deadly Wounds remains linear forever.
Next, treating wounds takes an entire hour. An hour is a very, very long time, and functionally can't be used between normal fights, residing only in down-time or periods of rest before continuing an adventure. It puts an enormous stress on the duration of buffs, even longer lasting buffs. An hour cuts out the equivalent of 6 caster levels of duration from a spell that lasts 10 minutes per level!
Finally, deadly wounds can only be treated once every 24 hours per creature. This makes continual treatment impossible, and further limits the already very slight recovery granted by the option. As a result, it's very rare to see anyone actually use the Treat Deadly Wounds action, instead consigning all healing to magic. It's preferable to take a nap and whack everyone with a healing wand until their wounds go away, and I think that's quite disappointing. The alternative presented here retains some limits on time- physical medical care is never going to be the instant cure-all that a magical salve is, after all- but hopes to provide fast enough recovery that it's competitive with relying on wands. ## The Rules **Treat Wounds:** You spend 10 minutes treating one injured living creature. You may treat your own wounds. The treated creature is unable to be treated by Treat Wounds for 1 hour, starting when your treatment begins. At the end of the 10 minute treatment period, make a Heal check. The Heal DC is usually 15, but you may suffer a circumstance penalty for especially poor conditions, such as an unsanitary space to operate in, a raging storm, or magically cursed wounds. If the Heal check is successful, the treated creature recovers hit points equal to 2d6 plus your margin of success (for example, a result of 24 on such a Heal check succeeds by 9, and restores 2d6+9 hit points). If the check was successful, you may continue treating the creature for a total of 1 hour to double the hit points recovered. If the result of your Heal check is 5 or less, the treated creature's wounds are made worse by your attempts and they suffer 1d8 damage.